全文获取类型
收费全文 | 4012篇 |
免费 | 1271篇 |
国内免费 | 511篇 |
专业分类
化学 | 1059篇 |
晶体学 | 49篇 |
力学 | 517篇 |
综合类 | 44篇 |
数学 | 773篇 |
物理学 | 3352篇 |
出版年
2024年 | 27篇 |
2023年 | 40篇 |
2022年 | 97篇 |
2021年 | 106篇 |
2020年 | 134篇 |
2019年 | 115篇 |
2018年 | 144篇 |
2017年 | 168篇 |
2016年 | 177篇 |
2015年 | 187篇 |
2014年 | 262篇 |
2013年 | 404篇 |
2012年 | 273篇 |
2011年 | 333篇 |
2010年 | 254篇 |
2009年 | 257篇 |
2008年 | 286篇 |
2007年 | 279篇 |
2006年 | 265篇 |
2005年 | 243篇 |
2004年 | 193篇 |
2003年 | 180篇 |
2002年 | 200篇 |
2001年 | 165篇 |
2000年 | 160篇 |
1999年 | 131篇 |
1998年 | 115篇 |
1997年 | 94篇 |
1996年 | 73篇 |
1995年 | 69篇 |
1994年 | 59篇 |
1993年 | 52篇 |
1992年 | 38篇 |
1991年 | 24篇 |
1990年 | 20篇 |
1989年 | 14篇 |
1988年 | 13篇 |
1987年 | 13篇 |
1986年 | 14篇 |
1985年 | 16篇 |
1984年 | 23篇 |
1983年 | 8篇 |
1982年 | 16篇 |
1981年 | 16篇 |
1980年 | 5篇 |
1979年 | 10篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1974年 | 5篇 |
排序方式: 共有5794条查询结果,搜索用时 328 毫秒
21.
Robert J. Rubin 《Journal of statistical physics》1991,65(5-6):1207-1216
A one-dimensional lattice random walk in the presence ofm equally spaced traps is considered. The step length distribution is a symmetric exponential. An explicit analytic expression is obtained for the probability that the random walk will be trapped at thejth trapping site. 相似文献
22.
高压电场作用下乙醇-水溶液体系变化红外光谱分析 总被引:1,自引:0,他引:1
本文报道了用红外光谱分析电磁场作用下乙醇 水溶液体系变化情况。分析结果表明 :当乙醇溶液受到 2 0kV·cm- 1 的交变电磁场处理 (5 0Hz)时 ,分子之间的氢键缔合先增大后减少 ;高乙醇含量溶液受到同样强度电场较长时间处理时 ,有乙醇发生氧化反应 ,从红外谱中可看到νCO 峰及ν(OH) (H2 O) 峰的出现 ;经处理后的溶液自然放置 7天再测定 ,其红外谱图基本保持不变。文中对各出现变化的峰进行了分析 ,并对其机理进行了推导 相似文献
23.
24.
25.
Tiago Buckup Timo Lebold Alexander Weigel Wendel Wohlleben Marcus Motzkus 《Journal of photochemistry and photobiology. A, Chemistry》2006,180(3):314-321
Biomolecules very often present complex energy deactivation networks with overlapping electronic absorption bands, making their study a difficult task. This can be especially true in transient absorption spectroscopy when signals from bleach, excited state absorption and stimulated emission contribute to the signal. However, quantum control spectroscopy can be used to discriminate specific electronic states of interest by applying specifically designed laser pulses. Recently, we have shown the control of energy flow in bacterial light-harvesting using shaped pump pulses in the visible and the selective population of pathways in carotenoids using an additional depletion pulse in the transient absorption technique. Here, we apply a closed-loop optimization approach to β-carotene using a spatial light modulator to decipher the energy flow network after a multiphoton excitation with a shaped ultrashort pulse in the near-IR. After excitation, two overlapping bands were detected and identified as the S1 state and the first triplet state T1. Using the transient absorption signal at a specific probe delay as feedback, the triplet signal could be optimized over the singlet contribution. 相似文献
26.
KANG Zihua WANG Mingwei QIAN Jiamei RAO Jun LI Xiujuan ZHENG Tieliu WANG Xuehua 《核工业西南物理研究院年报(英文版)》2004,(1):73-76
Lower hybrid wave (LHW), electro cyclotron (EC) and neutral beam injection (NBI) etc. are the important methods of auxiliary heating. They would be devoted to the HL-2A tokamak step by step. In order to satisfy the debug of each system and the need of the experiment, the system should be equipped with high voltage pulse power (HVPP) according to the requirement. 相似文献
27.
Unusual current‐voltage characteristics of single crystalline and bicrystalline La0.7Ca0.3MnO3 films
The current‐voltage characteristics of single crystalline and bicrystalline La0.7Ca0.3MnO3 films were measured and analyzed. Several epitaxial films, as well as 45° [001]‐tilt grain boundaries, display current‐voltage characteristics which are asymmetric with respect to polarity reversal of the bias current. One epitaxial film has a polarity dependent resistance of ~340kΩ and of ~670kΩ in forward and in reverse direction, respectively. 相似文献
28.
M. Ismail A. Farraga H. A. Abdusalam Th. El-Sherbini 《International Journal of Theoretical Physics》2004,43(1):111-125
The scattering of electrons by atomic copper has been studied using Born approximation and the concept of the generalized oscillator strength (GOS). Differential and total cross-sections for the excitation of the 3d10 4p2 P state are calculated at incident energies of 100 eV and are compared with other available experimental and theoretical data. The agreement between our calculation for the differential cross-section and the available experimental results is fairly good at the forward angles, while the agreement at large angles is poor. The calculated total cross-sections are compared with the experimental data and those predicted by several theories. It is found that our calculation for the total cross-sections are in a good agreement with the close coupling calculation of Msezane and Henry (1986a, Physical Review A
33, 1631) for incident energies greater than 20 eV. The integrated cross-section measurements of Ismail and Teubner (1995, Journal of Physics B: Atomic, Molecular and Optical Physics
28, 4164) are in good agreement with the present calculation. 相似文献
29.
双核系统核子转移驱动势与复合核的最佳激发能 总被引:2,自引:1,他引:1
计算了以208Pb为靶的一系列重离子熔合反应双核系统核子转移驱动势.它制约由输运方程所支配的核子转移速率,因而确定了双核系统形成复合核的几率.并由此可确定形成复合核所必须的最低激发能,即形成最稳定复合核的最佳激发能,得到了与已知实验值基本符合的结果. Particle transfer driven potentials in Di nuclear System (DNS) in heavy ion collisions based on 208Pb target are calculated. The driven potential controls the particle transfer velocity in the process governed by the diffusion equation, and as a consequence determines the compound nuclear formation probability of DNS. The minimum excitation energy to form a compound nucleus, which is the optimum excitation energy to form the most stable compound nucleus, has been calculated, and the results are basica... 相似文献
30.